CN114284637A

CN114284637A - Metal composite film and preparation method thereof

Info

Publication number: CN114284637A
Application number: CN202111647964.1A
Authority: CN
Inventors: 庄志; 张茜; 黎秋生; 冶成良; 程跃
Original assignee: Jiangsu Ruijie New Material Technology Co ltd
Current assignee: Jiangsu Ruijie New Material Technology Co ltd
Priority date: 2021-12-30
Filing date: 2021-12-30
Publication date: 2022-04-05
Also published as: WO2023123822A1

Abstract

The invention provides a metal composite film, which comprises: a metal layer, a first adhesive layer, and a first heat-sealing resin layer, wherein the first adhesive layer is arranged between the metal layer and the first heat-sealing resin layer, the first adhesive layer at least contains a curing agent and acid modified polypropylene, the curing agent contains more than 50 wt% of hexamethylene diisocyanate, the hexamethylene diisocyanate self-polymerizes into trimers, the hexamethylene diisocyanate having a functionality of 3.0 to 4.5, the acid-modified polypropylene contains polypropylene resin which is modified by grafting treatment with carboxylic acid or anhydride thereof, the acid value of the acid-modified polypropylene is 1 to 5, the melting point is 70 to 130 ℃, the weight average molecular weight is 10 to 25 ten thousand, the ratio NCO/COOH of the number of moles of isocyanate groups (NCO value) in the curing agent to the number of moles of carboxyl groups (COOH value) in the acid-modified polypropylene is 1.0 to 5.0.

Description

Metal composite film and preparation method thereof

Technical Field

The invention relates to the technical field related to battery packaging materials, in particular to a metal composite film layer and a preparation method thereof.

Background

Currently, lithium ion batteries are mainly classified into three categories, namely square, cylindrical and soft packages according to the appearance. The square and cylindrical shells mainly adopt aluminum alloy, stainless steel and the like, while the soft-packaged shell adopts a metal composite film formed by laminating metal and resin, so that the problem of inflexible appearance design of the hard-packaged battery is greatly improved. The soft-packaged metal composite film mainly comprises two types, namely a dry product, wherein the dry product comprises an outer base material resin layer, an outer adhesive layer, a middle metal layer, an inner adhesive layer and an inner heat-sealing resin layer from outside to inside in sequence; the other is a hot-melt product, which comprises an outer base resin layer, an outer adhesive layer, an intermediate metal layer and an inner heat-sealing resin layer in sequence from outside to inside.

Polypropylene is a common material in the inner adhesive layer. The inner adhesive layer can enable the middle metal layer and the inner heat-sealing resin layer to have certain composite strength, electrolyte resistance strength, two-side sealing tolerance and insulativity, so that electrolyte permeation and short circuit are prevented, and the performance of the inner adhesive layer has great influence on the performance of the battery. The adhesive used for the inner adhesive layer in the battery outer package at present is easily corroded by electrolyte of contents when in use, and the peeling strength between the intermediate metal layer and the internally heat-welded resin layer is easily reduced under long-term storage. In addition, the heat resistance also tends to decrease. The main reason for these problems is the choice of curing agent, generally Hexamethylene Diisocyanate (HDI), but without taking into account its functionality. Although HDI is used, the catalyst selection and the control of reaction conditions vary from one supplier to another, and usually the trimer product obtained is a mixture of a plurality of components, with different purity, resulting in great variation of performance. The peeling phenomenon of the intermediate metal layer and the internal heat-sealing resin layer caused by the destruction of the internal adhesive layer is easy to occur during the long-term storage, and the use safety is seriously influenced.

Disclosure of Invention

The invention aims to ensure that the outer package of the battery has good bonding performance and sealing performance in an electrolyte environment, so that a chemical system in the battery can stably work, and the basic safety of the battery is ensured.

Accordingly, the present invention provides a metal composite film comprising: a metal layer, a first adhesive layer, and a first heat-sealing resin layer, wherein the first adhesive layer is arranged between the metal layer and the first heat-sealing resin layer, the first adhesive layer at least contains a curing agent and acid modified polypropylene, the curing agent contains more than 50 wt% of hexamethylene diisocyanate, the hexamethylene diisocyanate self-polymerizes into trimers, the hexamethylene diisocyanate having a functionality of 3.0 to 4.5, the acid-modified polypropylene contains polypropylene resin which is modified by grafting treatment with carboxylic acid or anhydride thereof, the acid value of the acid-modified polypropylene is 1 to 5, the melting point is 70 to 130 ℃, the weight average molecular weight is 10 to 25 ten thousand, the ratio NCO/COOH of the number of moles of isocyanate groups (NCO value) in the curing agent to the number of moles of carboxyl groups (COOH value) in the acid-modified polypropylene is 1.0 to 5.0.

According to the invention, through selecting the physical properties of the acid modified polypropylene and the functionality of the curing agent, an optimal parameter range is found, so that the liquid-resistant peeling strength and the liquid-resistant heat sealing strength of the formed adhesive layer are improved, the performance is better, and the liquid-resistant performance of the adhesive layer and the liquid-resistant heat sealing strength in an electrolytic environment of electrolyte as a content after heat sealing are met.

Drawings

FIG. 1 is a schematic cross-sectional view of a metal composite film according to an embodiment of the present invention;

FIG. 2 is a graph showing the peel strength of the composite products of comparative examples 1 to 9 and comparative examples 1 to 10 after being soaked in an aqueous solution of 1000PPM in total electrolyte mass at a temperature of 85 ℃;

FIG. 3 is a graph showing the peel strength maintenance rates measured after the composite products of comparative examples 1 to 9 and comparative examples 1 to 10 were immersed in an aqueous solution of 1000PPM of the total mass of the electrolyte at a temperature of 85 ℃;

FIG. 4 is a graph showing the initial peel strength of the composite products of comparative examples 1 to 9 and comparative examples 1 to 10 and the peel strength measured after being left at different temperatures for 1 minute; and

FIG. 5 is a graph showing the peel strength maintenance rates of the composite products of comparative examples 1 to 9 and comparative examples 1 to 10 after being left at different temperatures for 1 minute.

Description of component reference numerals

(1) Metal layer

(2) First adhesive layer

(3) A first heat-sealing resin layer

(4) First anti-corrosion layer

(5) Second anti-corrosion layer

(6) Second adhesive layer

(7) Second heat-sealing resin layer

Detailed Description

The following detailed description of embodiments of the invention refers to the accompanying drawings. It should be understood that the detailed description and specific examples, while indicating the present invention, are given by way of illustration and explanation only, not limitation.

The endpoints of the ranges and any values disclosed herein are not limited to the precise range or value, and such ranges or values should be understood to encompass values close to those ranges or values. For ranges of values, between the endpoints of each of the ranges and the individual points, and between the individual points may be combined with each other to give one or more new ranges of values, and these ranges of values should be considered as specifically disclosed herein.

As shown in fig. 1, one embodiment of the present invention provides a metal composite film, which at least includes: the adhesive comprises a metal layer (1), a first adhesive layer (2) and a first hot-melt resin layer (3), wherein the first adhesive layer (2) is arranged between the metal layer (1) and the first hot-melt resin layer (3), the first adhesive layer (2) at least comprises a curing agent and acid-modified polypropylene, the curing agent contains more than 50 wt% of hexamethylene diisocyanate, the hexamethylene diisocyanate is self-polymerized into a trimer, the functionality of the hexamethylene diisocyanate is 3.0-4.5, the acid-modified polypropylene contains polypropylene resin, the polypropylene resin is modified by grafting carboxylic acid or anhydride thereof, the acid-modified polypropylene has an acid value of 1-5, a melting point of 70-130 ℃, a weight-average molecular weight of 10-25 ten thousand, and the ratio of the isocyanate group mole number (NCO value) in the curing agent to the carboxyl group mole number (NCO value) in the acid-modified polypropylene is NCO/COOH Is 1.0 to 5.0.

Since the first adhesive layer (2) is formed by curing reaction of the acid-modified polypropylene and the curing agent, the curing agent has impurities having a carbon number different from that of the reaction product in addition to the desired reaction product at the production stage. Since it is very difficult to remove this impurity, the trimer product in the curing agent is a multicomponent mixture. Based on this, "the functionality of hexamethylene diisocyanate" can be regarded as an indicator of the purity of the hexamethylene diisocyanate.

In the present embodiment, when the functionality of the hexamethylene diisocyanate is less than the minimum value 3 of the defined range, a large amount of linear reaction products are generated, and the linear reaction products are decomposed by the penetration of the electrolyte and the generation of hydrofluoric acid. On the other hand, when the functionality of the hexamethylene diisocyanate exceeds the maximum value of 4.5 of the defined range, the number of linear reaction components is reduced, but the number of reaction products in a state of a compact three-dimensional structure is increased; the internal stress of the first adhesive layer (2) is increased by the occurrence of a dense structure, and the peel strength between the metal layer (1) and the first heat-sealing resin layer (3) tends to be reduced.

The "acid value of the acid-modified polypropylene" represents the number of milligrams of potassium hydroxide (KOH) required to neutralize 1 gram of the acid-modified polypropylene, and thus the unit thereof is not shown but is actually mg KOH/g.

In the present embodiment, when the acid value of the acid-modified polypropylene is less than the minimum value of 1.0mg KOH/g defined in the range, the number of curing reaction points with the curing agent is small, and the adhesiveness between the metal layer (1) and the first heat-sealing resin layer (3) is unstable. On the contrary, when the acid value of the acid-modified polypropylene exceeds the maximum value of the defined range of 5.0mg KOH/g, the curing reaction with the curing agent is too severe to form a hard layer structure, which deteriorates the bending resistance, reduces the flexibility of the entire metal composite film, or causes cracks by bending, thereby causing peeling of the metal layer (1) and the first thermal welding resin layer (3).

In the present embodiment, when the melting point of the acid-modified polypropylene is less than the minimum value 70 ℃ of the defined range, the heat resistance is lowered, and the metal layer (1) and the first heat-fusible resin layer (3) are likely to be peeled off at a high temperature. On the other hand, when the melting point of the acid-modified polypropylene exceeds the maximum 130 ℃ of the defined range, the heat resistance is improved, but when the acid-modified polypropylene reacts with a curing agent, a hard layer structure is easily formed, and the flexibility of the metal composite film is poor, or cracks are generated by bending, and the metal layer (1) and the first heat-sealing resin layer (3) are peeled off.

In the present embodiment, when the weight average molecular weight of the acid-modified polypropylene is less than the minimum value of 10 ten thousand within the defined range, the fluidity is improved upon heating, the thickness is significantly reduced upon heat sealing, and the adhesion strength between the metal layer (1) and the first heat-sealing resin layer (3) is reduced, thereby causing a problem of insufficient sealing properties. On the contrary, when the weight average molecular weight of the acid-modified polypropylene exceeds 25 ten thousand, the metal layer (1) and the first heat-sealing resin layer (3) form a hard layer structure, so that the bending resistance is deteriorated, the flexibility of the metal composite film is reduced, or cracks are generated by bending, and the metal layer (1) and the first heat-sealing resin layer (3) are peeled off.

The first adhesive layer (2) is formed by reacting acid-modified polypropylene with hexamethylene diisocyanate, specifically, Carboxyl (COOH) groups obtained by graft polymerization of the acid-modified polypropylene react with isocyanate (NCO) groups of the hexamethylene diisocyanate, so that the first adhesive layer (2) maintains the characteristics of resistance to content electrolytes, chemicals, heat and the like. When the carboxyl group content (COOH value) of the acid-modified polypropylene and the isocyanate group content (NCO value) of the curing agent are in an appropriate range, the first adhesive layer (2) can exhibit excellent adhesion, chemical resistance, and heat resistance. "ratio NCO/COOH" means the ratio of the NCO value to the COOH value.

In the present embodiment, when the ratio NCO/COOH is less than the minimum value of 1.0 defined as the range, the isocyanate group represented by the curing agent is smaller than the carboxyl group represented by the acid-modified polypropylene. In this case, since the acid-modified polypropylene is present in excess, unreacted acid-modified polypropylene increases, and the initial peel strength of the metal layer (1) and the first heat-sealing resin layer (3) improves. However, the first adhesive layer (2) is unstable in chemical resistance due to the increase in unreacted acid-modified polypropylene. In addition, since the first adhesive layer (2) is easily corroded by the content electrolyte due to the unstable chemical resistance, the peeling strength of the metal layer (1) and the first heat-sealing resin layer (3) is reduced during long-term storage, and the metal layer (1) and the first heat-sealing resin layer (3) may be peeled off. In addition, the heat resistance tends to be lowered.

In this embodiment, when the ratio NCO/COOH exceeds the maximum value of 5.0 defined range, it means that the isocyanate group of the curing agent is more abundant than the carboxyl group of the acid-modified polypropylene. In this case, since the curing agent is present in excess, the amount of unreacted curing agent increases, and the amount of a cross-linked curing agent increases, so that the first adhesive layer (2) tends to become hard and brittle. Accordingly, the initial peel strength of the metal layer (1) and the first heat-sealing resin layer (3) tends to be reduced. In addition, since the first adhesive layer (2) becomes hard and brittle and the initial peel strength of the metal layer (1) and the first heat-fusion resin layer (3) is reduced, the first adhesive layer (2) is easily corroded by the content electrolyte and becomes harder and brittle, and the flexibility is insufficient, so that the metal layer (1) and the first heat-fusion resin layer (3) are easily peeled off due to the destruction of the first adhesive layer (2) during long-term storage.

As described above, the polypropylene resin is modified by graft treatment with a carboxylic acid or an acid anhydride thereof to graft-polymerize an acid-modified polypropylene with a carboxyl group (COOH). In this embodiment, the carboxylic acid may include one or more of maleic acid, fumaric acid, acrylic acid, and methacrylic acid; and the anhydride may include one or more of maleic anhydride, fumaric anhydride, acrylic anhydride, and methacrylic anhydride.

In the present embodiment, the metal layer (1) and the first thermal welding resin layer (3) are not important for protection of the present application, and are only illustrated for simplicity and are not repeated.

For example, the metal layer (1) may be an aluminum foil, an aluminum alloy foil, a nickel-plated iron foil, or a stainless steel foil, but is not limited thereto; the thickness of the metal layer (1) may be 30 to 50 μm, preferably 35 to 40 μm, but is not limited thereto.

For example, the first thermal welding resin layer (3) comprises, in order from one side close to the first adhesive layer (2) to the other side far from the first adhesive layer (2): an outer resin layer, an intermediate resin layer, and an inner resin layer, but not limited thereto.

For example, the outer resin layer includes random copolymer polypropylene, which may have a melting point of 140 to 160 ℃, preferably 145 to 155 ℃, more preferably 151 ℃, and a 230 ℃ melt index MFR of 4.5 to 6.5g/10min, preferably 5 to 6 ℃ g/10min, more preferably 5.5g/10min, but is not limited thereto. Furthermore, the side of the outer resin layer close to the first adhesive layer (2) may be corona treated.

For example, the middle resin layer may include block copolymerized polypropylene, random copolymerized polypropylene, propylene-butylene composed polymer elastomer, and amorphous propylene-based elastomer. The melting point of the block copolymer polypropylene may be 150 to 170 ℃, preferably 155 to 165 ℃, more preferably 162 ℃, the 230 ℃ melt index MFR of the block copolymer polypropylene may be 1 to 4g/10min, preferably 1.5 to 3g/10min, more preferably 2g/10min, and the content of the block copolymer polypropylene with respect to the middle resin layer may be 40 to 60 wt%, preferably 45 to 55 wt%, more preferably 50 wt%, but is not limited thereto. The melting point of the random copolymer polypropylene may be 140 to 170 ℃, preferably 150 to 160 ℃, more preferably 155 ℃, the 230 ℃ melt index MFR of the random copolymer polypropylene may be 4 to 7g/10min, preferably 4.5 to 6g/10min, more preferably 5g/10min, and the content of the random copolymer polypropylene with respect to the middle resin layer may be 10 to 30 wt%, preferably 15 to 25 wt%, more preferably 20 wt%, but is not limited thereto. The melting point of the propylene-butene-composed polymer elastomer may be 150 to 170 ℃, preferably 155 to 165 ℃, more preferably 160 ℃, the 230 ℃ melt index MFR of the propylene-butene-composed polymer elastomer may be 8 to 12g/10min, preferably 9 to 10g/10min, more preferably 9.5g/10min, and the content of the propylene-butene-composed polymer elastomer with respect to the middle resin layer may be 10 to 30 wt%, preferably 15 to 25 wt%, more preferably 20 wt%, but is not limited thereto. The melt index MFR at 230 ℃ of the non-crystalline propylene-based elastomer may be 2 to 4g/10min, preferably 2.5 to 3.5g/10min, more preferably 3g/10min, and the content of the non-crystalline propylene-based elastomer with respect to the intermediate resin layer may be 5 to 15 wt%, preferably 8 to 12 wt%, more preferably 10 wt%, but is not limited thereto.

For example, the inner resin layer may include random copolymer polypropylene, which may have a melting point of 135 to 155 ℃, preferably 140 to 150 ℃, more preferably 145 ℃, and a 230 ℃ melt index MFR of 10 to 15g/10min, preferably 11 to 13g/10min, more preferably 12g/10min, but is not limited thereto.

Further, the thickness ratio of the outer resin layer, the intermediate resin layer, and the inner resin layer may be (1 to 5): (4 to 8):1, preferably (2 to 4): (5 to 7):1, more preferably 3:6:1, but is not limited thereto.

As shown in fig. 1, the metal composite film of the present embodiment may further include a first anti-corrosion layer (4), a second anti-corrosion layer (5), a second adhesive layer (6), and a second thermal welding resin layer (7).

In the present embodiment, the first anti-corrosion layer (4), the second anti-corrosion layer (5), the second adhesive layer (6), and the second heat-sealing resin layer (7) are not important for protection of the present application, and are only illustrated here for simplicity and are not described in detail.

For example, the second adhesive layer (6) is formed on the side of the metal layer (1) opposite to the first adhesive layer (2), the second heat-sealing resin layer (7) is formed on the side of the second adhesive layer (6) opposite to the metal layer (1), the first corrosion-prevention layer (4) is formed between the metal layer (1) and the first adhesive layer (2), and the second corrosion-prevention layer (5) is formed between the metal layer (1) and the second adhesive layer (6).

For example, the second adhesive layer (6) may include a polyurethane-modified polyester polyol and an aromatic isocyanate-based compound, or may include a polyurethane-modified polyester polyol, a polyester polyol and an aromatic isocyanate-based compound. The ratio of the number of moles of isocyanate groups (NCO value) in the aromatic isocyanate-based compound to the number of moles of hydroxyl groups (OH value) in the polyurethane-modified polyester polyol and/or polyester polyol may be 15 to 30, preferably 20 to 25, more preferably 21, but is not limited thereto. Further, an example of the aromatic isocyanate-based compound may be Toluene Diisocyanate (TDI), but is not limited thereto. In the case where the second adhesive layer (6) includes a polyester polyol and an aromatic isocyanate compound, the polyester polyol may include a first noncrystalline polyester polyol and a second noncrystalline polyester polyol, and the weight ratio between the first noncrystalline polyester polyol and the second noncrystalline polyester polyol may be (4 to 1):1, preferably (3 to 1.5):1, more preferably 2:1, but is not limited thereto. Also, the weight average molecular weight of the first amorphous polyester polyol may be 7000 to 9000, preferably 7500 to 8500, more preferably 8000, the Tg temperature of the first amorphous polyester polyol may be 70 to 90 ℃, preferably 75 to 85 ℃, more preferably 79 ℃, and the hydroxyl value of the first amorphous polyester polyol may be 10 to 20mg KOH/g, preferably 13 to 18mg KOH/g, more preferably 16mg KOH/g, but is not limited thereto; the weight average molecular weight of the second non-crystalline polyester polyol may be 5500 to 7500, preferably 6000 to 7000, more preferably 6500, the Tg temperature of the second non-crystalline polyester polyol may be-10 to 5 ℃, preferably-7 to 0 ℃, more preferably-3 ℃, and the hydroxyl value of the second non-crystalline polyester polyol may be 5 to 15mg KOH/g, preferably 7.5 to 12.5mg KOH/g, more preferably 10mg KOH/g, but is not limited thereto.

For example, the side of the second layer of heat-sealing resin (7) close to the second layer of adhesive (6) may be corona-treated.

For example, each of the first corrosion prevention layer (4) and the second corrosion prevention layer (5) may include a trivalent chromium compound, which may include one or more of chromium nitrate, chromium phosphate, chromium fluoride, and chromium chloride, an inorganic acid, which may include one or more of nitric acid and phosphoric acid, and an organic resin, which may include one or more of polyacrylic acid-based resin and polyvinyl alcohol. Further, examples of the polyacrylic resin may be one or more of polyacrylic acid, polymethyl acrylate, a copolymer of acrylic acid and maleic acid, a copolymer of acrylic acid and styrene, and sodium salt, ammonium salt, and the like derivatives thereof, and the weight average molecular weight of the polyacrylic resin may be 1 to 80 ten thousand, but is not limited thereto. Further, the mass ratio between the trivalent chromium compound, the inorganic acid and the organic resin may be (18 to 60): (3 to 60): (6 to 60), but is not limited thereto. Further, the mass ratio between the trivalent chromium compound and the organic resin may be (3 to 100): 10. under the above conditions, each of the first corrosion prevention layer (4) and the second corrosion prevention layer (5) may further include a fluoride, the fluoride may include at least chromium fluoride, and the mass ratio between the trivalent chromium compound, the inorganic acid, the organic resin, and the fluoride may be (18 to 60): (3 to 60): (6 to 60): (0 to 10), the corresponding value of fluoride is not 0, but is not limited thereto.

For example, each of the first corrosion prevention layer (4) and the second corrosion prevention layer (5) may include a trivalent chromium compound, which may include one or more of chromium nitrate, chromium fluoride, chromium chloride, and chromium phosphate, an inorganic acid, which may include one or more of nitric acid and hydrofluoric acid, and an organic resin, which may include at least polyvinyl alcohol, but is not limited thereto. Further, the mass ratio between the trivalent chromium compound, the inorganic acid and the organic resin may be (24 to 40): (1 to 8): (10 to 12), but is not limited thereto. Further, the mass ratio between the trivalent chromium compound and the organic resin may be (2 to 4): 1. under the above conditions, each of the first corrosion prevention layer (4) and the second corrosion prevention layer (5) may further include titanate, and the mass ratio between the trivalent chromium compound, the inorganic acid, the organic resin, and the titanate may be (24 to 40): (1 to 8): (10 to 12): (0 to 5), the corresponding value of titanate is not 0, but is not limited thereto.

For example, the first corrosion prevention layer (4) and the second corrosion prevention layer (5) may each include an aminated phenol polymer, a trivalent chromium compound, and a phosphorus compound. In the first anti-corrosion layer (4) and the second anti-corrosion layer (5) per 1m²The aminated phenol polymer may account for 1 to 200mg, the chromium element in the trivalent chromium compound may account for 0.5 to 50mg, and the phosphorus element in the phosphorus compound may account for 0.5 to 50mg, but not limited thereto.

For example, the first and second corrosion protection layers (4, 5) may each include a first and second corrosion protection sub-layer, a first one of the first corrosion protection layers (4) being formed adjacent to one side of the metal layer (1), a second one of the first corrosion protection layers (4) being formed adjacent to the other side of the first adhesive layer (2), a first one of the second corrosion protection layers (5) being formed adjacent to one side of the metal layer (1), and a second one of the second corrosion protection layers (5) being formed adjacent to the other side of the second adhesive layer (6). Furthermore, whether the first corrosion protection sublayer in the first corrosion protection layer (4) or the second corrosion protection layer (5) may comprise cerium oxide, phosphoric acid or phosphate, and whether the second corrosion protection sublayer in the second corrosion protection layer (5) or the second corrosion protection sublayer in the second corrosion protection layer (5) may comprise a polymeric cationic or anionic polymer, but is not limited thereto. In addition, in the case where the first anti-corrosion sublayer includes cerium oxide and phosphoric acid or phosphate, 1 to 100 parts by mass of phosphoric acid or phosphate may be occupied in the presence of 100 parts by mass of cerium oxide.

In the present embodiment, by selecting the physical properties of the acid-modified polypropylene and the functionality of the curing agent, an optimal parameter range is found, so that the liquid-resistant peel strength and the liquid-resistant heat seal strength of the adhesive layer are improved, and the performance is better, thereby satisfying the liquid-resistant performance of the adhesive layer and the liquid-resistant heat seal strength after heat sealing and in the electrolytic environment of the electrolyte as the content.

Based on the characteristics of the metal composite film, another embodiment of the present invention provides a battery exterior material including the metal composite film, wherein the metal composite film is in contact with an electrolyte of a battery through a side close to the first heat-sealing resin layer (3).

In addition, another embodiment of the present invention provides a method for preparing the metal composite film, including: -providing the metal layer (1); forming the first adhesive layer (2) on the metal layer (1); and forming the first thermal welding resin layer (3) on one side of the first adhesive layer (2) opposite to the metal layer (1).

For example, when the first adhesive layer (2) is formed on the metal layer (1), a solution containing the components of the first adhesive layer (2) may be coated on the metal layer (1), and then the solution containing the components of the first adhesive layer (2) may be dried.

For example, when the first thermal welding resin layer (3) is formed on the side of the first adhesive layer (2) opposite to the metal layer (1), the side of the first adhesive layer (2) opposite to the metal layer (1) and the first thermal welding resin layer (3) may be thermally composited, and then cured. The temperature of the thermal compounding may be 80 to 100 c, preferably 90 c, and the temperature of the aging treatment may be 40 to 60 c, preferably 50 c, and the time of the aging treatment may be 6 to 10 days, preferably 7 days, but is not limited thereto.

In this embodiment, between providing the metal layer (1) and forming the first adhesive layer (2) on the metal layer (1), the method further includes forming the first anti-corrosion layer (4) or the second anti-corrosion layer (5) on both sides of the metal layer (1). And the first adhesive layer (2) is formed on the metal layer (1) in anticipation of forming the first adhesive bondThe agent layer (2) is formed on one side, and the second anti-corrosion layer (5) is formed on the other side of the metal layer (1) relative to the first adhesive layer (2) which is expected to be formed. Either the first corrosion protection layer (4) or the second corrosion protection layer (5) may be applied first to the metal layer (1) with a solution containing the components of the first corrosion protection layer (4) or the second corrosion protection layer (5) and then dried by hot baking. The amount of the wet film to be coated of the solution may be 3 to 7g/m²Preferably 5g/m². The temperature of the heat drying may be 180 to 200 c, preferably 190 c, and the time of the heat drying may be 1 to 3 minutes, preferably 2 minutes.

In this embodiment, after providing the metal layer (1), the method further includes forming the second adhesive layer (6) on a side of the metal layer (1) opposite to the first adhesive layer (2); and forming the second thermal welding resin layer (7) on one side of the second adhesive layer (6) opposite to the metal layer (1).

For example, in forming the second adhesive layer (6) on the side of the metal layer (1) opposite to the first adhesive layer (2), a composition containing the second adhesive layer (6) may be applied on the side of the metal layer (1) opposite to the first adhesive layer (2).

For example, when the second thermal welding resin layer (7) is formed on the side of the second adhesive layer (6) opposite to the metal layer (1), the second thermal welding resin layer (7) and the second adhesive layer (6) may be thermally compounded first, and then cured. The temperature of the aging treatment may be 50 to 70 c, preferably 60 c, and the time of the aging treatment may be 1 to 5 days, preferably 3 days, but is not limited thereto.

The following describes the process of combining the metal composite films proposed in the examples and comparative examples, and the disadvantages are complemented by the examples and comparative examples:

the composite metal composite film consists of an outer base material resin layer, an outer adhesive layer, an intermediate metal layer, an inner adhesive layer and an inner heat-sealing resin layer.

The laminating method comprises the following steps:

and carrying out corona treatment on the resin film of the outer base material resin layer in contact with the outer adhesive layer. Specifically, a two-component polyurethane adhesive (polyurethane-modified polyester polyol or polyester polyol and an aromatic isocyanate compound) is applied to one surface of a metal foil (e.g., aluminum foil, aluminum alloy foil, nickel-plated iron foil, stainless steel foil, etc.) to form an outer adhesive layer on the metal foil. And thermally compounding the outer adhesive layer on the metal foil and the outer base resin layer film, and curing at 60 ℃ for 3 days to form an outer base resin layer/outer adhesive layer/metal layer semi-finished product.

An outer adhesive layer was formed on one side of the metal foil by coating with an adhesive of the following formulation:

mixing amorphous polyester polyol with the weight-average molecular weight of 8000, Tg of 79 ℃ and the hydroxyl value of 16mg KOH/g and amorphous polyester polyol with the weight-average molecular weight of 6500, Tg of-3 ℃ and the hydroxyl value of 10mg KOH/g according to the weight ratio of 10:5, and adding Toluene Diisocyanate (TDI) to form external bonding mixed liquid with the NCO/OH ratio of 21.

And (3) performing antiseptic treatment on both sides of the metal in advance:

uniformly coating the mixture on two sides of the metal foil by a coating roller according to a certain proportion, and then baking for 2min at 190 ℃. The wet coating amount of the anticorrosive layer treatment liquid was 5g/m²The chromium content of the aluminum foil surface coating is 15mg/m²。

The compounding mode of the inner adhesive layer is as follows:

and an inner adhesive layer is compounded on the metal surface of the outer base material resin layer/the outer adhesive layer/the middle metal layer. The inner adhesive layer is a two-component adhesive, and is prepared by coating a mixture of solvent-type acid-modified polypropylene and a curing agent on an anti-corrosion treated metal surface relative to the outer base material resin in a composite film of the composite outer base material resin by a dry compounding method, drying to form the inner adhesive layer, thermally compounding the inner adhesive layer with the bonding surface of the thermal welding resin at 90 ℃, and curing at 50 ℃ for 7 days to form a composite finished product of the outer base material resin layer/the outer adhesive layer/the middle metal layer/the inner adhesive layer/the inner thermal welding resin layer.

The compounding mode of the internal heat welding resin layer is as follows:

the adhesive surface of the film of the inner heat-sealable resin layer in contact with the inner adhesive layer is subjected to corona treatment in advance. And finishing compounding the semi-finished product packaging material of the outer base material resin layer/the outer adhesive layer/the middle metal layer/the inner adhesive layer with the inner heat-welded resin layer in a dry compounding way, and aging for three days at the temperature of 60 ℃ to obtain the finished product lithium ion battery device outer packaging material. Specifically, the internally heat-sealing resin layer is composed of three layers, one surface of the internally heat-sealing resin layer, which is in contact with the internal adhesive layer, is subjected to corona treatment, and the internally heat-sealing resin layer has the structure that:

outer resin layer in contact with inner adhesive layer: a layer composed of a random copolymerized polypropylene having a melting point of 151 ℃ and an MFR (230 ℃) of 5.5g/10 min;

an intermediate resin layer: 50 wt% of a block copolymer polypropylene having a melting point of 162 ℃ and an MFR (230 ℃) of 2g/10 min; 20 wt% of a random copolymer polypropylene having a melting point of 155 ℃ and an MFR (230 ℃) of 5g/10 min; 20 wt% having a melting point of 160 ℃, an MFR (230 ℃) of 9.5g/10min and a density of 0.87g/cm³A polymer elastomer composed of propylene-butene; and 10 wt% of a non-crystalline propylene-based elastomer having MFR (230 ℃) of 3g/10 min;

inner resin layer: a layer composed of a random copolymerized polypropylene having a melting point of 145 ℃ and an MFR (230 ℃) of 12g/10 min;

the thickness ratio of three layers of resin from the outer layer contacting with the inner adhesive layer to the inner layer in the inner heat-sealing resin layer is 3:6: 1.

Example 1

The outer base resin layer is a 25 μm thick biaxially oriented nylon film which is compounded to a 35 μm thick intermediate metal layer 8021 series aluminum material having a surface wettability of 68dyn/cm by an adhesive. And performing anti-corrosion treatment on two sides of the metal layer to form an anti-corrosion layer, wherein the anti-corrosion treatment is carried out in such a way that the mass ratio of a trivalent chromium compound, inorganic acid and organic resin on the surface of the metal layer is 2:2: 1, the trivalent chromium compound is chromium phosphate, the inorganic acid is nitric acid, and the organic resin is polyacrylic resin.

A solution-type mixture was prepared by mixing an anhydrous maleic anhydride-modified polypropylene solution having a weight-average molecular weight of 25 ten thousand, a melting point of 85 ℃ and an acid value of 2 with a curing agent containing 50% by weight or more of hexamethylene diisocyanate which self-polymerizes into trimers and has a functionality of 3.4 and a ratio NCO/COOH of the number of moles of isocyanate groups in the curing agent (NCO value) to the number of moles of carboxyl groups in the acid-modified polypropylene (COOH value) of 3.6. The resulting solution-type mixture was applied to the metal surface of the composite film of the composite outer substrate resin layer opposite to the outer substrate resin layer, dried to form an inner adhesive layer having a thickness of 2 μm, and then heat-compounded with a heat-fusible resin layer of 40 μm at a temperature of 90 ℃ and then cured at a temperature of 50 ℃ for 7 days to form a composite product of the outer substrate resin layer (25 μm)/outer adhesive layer (3 μm)/intermediate metal layer/inner adhesive layer/inner heat-fusible resin layer (40 μm). The adhesive surface of the three-layer heat-fusible resin film in contact with the inner adhesive layer is subjected to corona treatment in advance.

Example 2

The outer base resin layer is a 25 μm thick biaxially oriented nylon film which is compounded to a 40 μm thick intermediate metal layer 8079 series aluminum material having a surface wettability of 70dyn/cm by an adhesive. And performing anti-corrosion treatment on two sides of the metal layer to form an anti-corrosion layer, wherein the anti-corrosion treatment is carried out in such a way that the mass ratio of a trivalent chromium compound, inorganic acid and organic resin on the surface of the metal layer is 2:2: 1, the trivalent chromium compound is chromium phosphate, the inorganic acid is nitric acid, and the organic resin is polyacrylic resin.

A solution-type mixture was prepared by mixing an anhydrous maleic anhydride-modified polypropylene solution having a weight-average molecular weight of 25 ten thousand, a melting point of 85 ℃ and an acid value of 2 with a curing agent containing 50% by weight or more of hexamethylene diisocyanate which self-polymerizes into a trimer having a functionality of 3.1, and the ratio NCO/COOH of the number of moles of isocyanate groups in the curing agent (NCO value) to the number of moles of carboxyl groups in the acid-modified polypropylene (COOH value) was 3.6. The resulting solution-type mixture was applied to the metal surface of the composite film of the composite outer substrate resin layer opposite to the outer substrate resin layer, dried to form an inner adhesive layer having a thickness of 2 μm, and then heat-compounded with a heat-fusible resin layer of 40 μm at a temperature of 90 ℃ and then cured at a temperature of 50 ℃ for 7 days to form a composite product of the outer substrate resin layer (25 μm)/outer adhesive layer (3 μm)/intermediate metal layer/inner adhesive layer/inner heat-fusible resin layer (40 μm). The adhesive surface of the three-layer heat-fusible resin film in contact with the inner adhesive layer is subjected to corona treatment in advance.

Example 3

The outer substrate resin layer is a 25 mu m thick biaxially oriented nylon film which is compounded on a 38 mu m thick middle metal layer stainless steel foil through an adhesive, and the surface water contact angle of the film is 15 degrees. And performing anti-corrosion treatment on two sides of the metal layer to form an anti-corrosion layer, wherein the anti-corrosion treatment is carried out in such a way that the mass ratio of a trivalent chromium compound, inorganic acid and organic resin on the surface of the metal layer is 2:2: 1, the trivalent chromium compound is chromium phosphate, the inorganic acid is nitric acid, and the organic resin is polyacrylic resin.

A solution-type mixture was prepared by mixing an anhydrous maleic anhydride-modified polypropylene solution having a weight-average molecular weight of 25 ten thousand, a melting point of 85 ℃ and an acid value of 2 with a curing agent containing 50% by weight or more of hexamethylene diisocyanate which self-polymerizes into trimers and has a functionality of 4.2 and a ratio NCO/COOH of the number of moles of isocyanate groups in the curing agent (NCO value) to the number of moles of carboxyl groups in the acid-modified polypropylene (COOH value) of 3.6. The resulting solution-type mixture was applied to the metal surface of the composite film of the composite outer substrate resin layer opposite to the outer substrate resin layer, dried to form an inner adhesive layer having a thickness of 2 μm, and then heat-compounded with a heat-fusible resin layer of 40 μm at a temperature of 90 ℃ and then cured at a temperature of 50 ℃ for 7 days to form a composite product of the outer substrate resin layer (25 μm)/outer adhesive layer (3 μm)/intermediate metal layer/inner adhesive layer/inner heat-fusible resin layer (40 μm). The adhesive surface of the three-layer heat-fusible resin film in contact with the inner adhesive layer is subjected to corona treatment in advance.

Example 4

The composite film is formed by using an aluminum alloy foil, and both surfaces of the aluminum alloy foil are chemically treated in advance to form an anti-corrosion layer. The formation of the corrosion protection layer was the same as in example 1.

The outer substrate resin layer and the outer adhesive layer were laminated as in example 1.

A solution-type mixture was prepared by mixing an anhydrous maleic anhydride-modified polypropylene solution having a weight-average molecular weight of 12 ten thousand, a melting point of 75 ℃ and an acid value of 2 with a curing agent containing 50% by weight or more of hexamethylene diisocyanate which self-polymerizes into trimers and has a functionality of 3.4 and a ratio NCO/COOH of the number of moles of isocyanate groups in the curing agent (NCO value) to the number of moles of carboxyl groups in the acid-modified polypropylene (COOH value) of 3.6. The resulting solution-type mixture was applied to the metal surface of the composite film of the composite outer substrate resin layer opposite to the outer substrate resin layer, dried to form an inner adhesive layer having a thickness of 2 μm, and then heat-compounded with a heat-fusible resin layer of 40 μm at a temperature of 90 ℃ and then cured at a temperature of 50 ℃ for 7 days to form a composite product of the outer substrate resin layer (25 μm)/outer adhesive layer (3 μm)/intermediate metal layer/inner adhesive layer/inner heat-fusible resin layer (40 μm). The adhesive surface of the three-layer heat-fusible resin film in contact with the inner adhesive layer is subjected to corona treatment in advance.

Example 5

The outer base resin layer is a 25 μm thick biaxially oriented nylon film which is compounded to a 35 μm thick intermediate metal layer 8021 series aluminum material having a surface wettability of 68dyn/cm by an adhesive. And performing anticorrosion treatment on two surfaces of the metal layer to form an anticorrosion layer, wherein the anticorrosion treatment is performed in such a way that the mass ratio of a trivalent chromium compound, an inorganic acid and an organic resin on the surface of the metal layer is 15: 1: and 5, the trivalent chromium compound is chromium fluoride, the inorganic acid is hydrofluoric acid, and the organic resin is polyvinyl alcohol resin.

A solution-type mixture was prepared by mixing an anhydrous maleic anhydride-modified polypropylene solution having a weight-average molecular weight of 25 ten thousand, a melting point of 85 ℃ and an acid value of 2 with a curing agent containing 50% by weight or more of hexamethylene diisocyanate which self-polymerizes into trimers and has a functionality of 3.4, and the ratio NCO/COOH of the number of moles of isocyanate groups in the curing agent (NCO value) to the number of moles of carboxyl groups in the acid-modified polypropylene (COOH value) was 4.82. The resulting solution-type mixture was applied to the metal surface of the composite film of the composite outer substrate resin layer opposite to the outer substrate resin layer, dried to form an inner adhesive layer having a thickness of 2 μm, and then heat-compounded with a heat-fusible resin layer of 40 μm at a temperature of 90 ℃ and then cured at a temperature of 50 ℃ for 7 days to form a composite product of the outer substrate resin layer (25 μm)/outer adhesive layer (3 μm)/intermediate metal layer/inner adhesive layer/inner heat-fusible resin layer (40 μm). The adhesive surface of the three-layer heat-fusible resin film in contact with the inner adhesive layer is subjected to corona treatment in advance.

Example 6

The composite film is formed by using an aluminum alloy foil, and both surfaces of the aluminum alloy foil are chemically treated in advance to form an anti-corrosion layer. The formation of the corrosion protection layer was the same as in example 5.

The outer substrate resin layer and outer adhesive layer were laminated as in example 5.

A solution-type mixture was prepared by mixing an anhydrous maleic anhydride-modified polypropylene solution having a weight-average molecular weight of 25 ten thousand, a melting point of 85 ℃ and an acid value of 2 with a curing agent containing 50% by weight or more of hexamethylene diisocyanate which self-polymerizes into trimers and has a functionality of 3.4, and the ratio NCO/COOH of the number of moles of isocyanate groups in the curing agent (NCO value) to the number of moles of carboxyl groups in the acid-modified polypropylene (COOH value) was 1.36. The resulting solution-type mixture was applied to the metal surface of the composite film of the composite outer substrate resin layer opposite to the outer substrate resin layer, dried to form an inner adhesive layer having a thickness of 2 μm, and then heat-compounded with a heat-fusible resin layer of 40 μm at a temperature of 90 ℃ and then cured at a temperature of 50 ℃ for 7 days to form a composite product of the outer substrate resin layer (25 μm)/outer adhesive layer (3 μm)/intermediate metal layer/inner adhesive layer/inner heat-fusible resin layer (40 μm). The adhesive surface of the three-layer heat-fusible resin film in contact with the inner adhesive layer is subjected to corona treatment in advance.

Example 7

The outer base resin layer is a 25 μm thick biaxially oriented nylon film which is compounded to a 35 μm thick intermediate metal layer 8021 series aluminum material having a surface wettability of 68dyn/cm by an adhesive. And performing anticorrosion treatment on two surfaces of the metal layer to form an anticorrosion layer, wherein the anticorrosion treatment is to ensure that the mass ratio of the trivalent chromium compound, the inorganic acid, the fluoride and the aminated phenol resin on the surface of the metal layer is 15:2:2: 3. The trivalent chromium compound is chromium nitrate and the inorganic acid is phosphoric acid.

A solution-type mixture was prepared by mixing an anhydrous maleic anhydride-modified polypropylene solution having a weight-average molecular weight of 25 ten thousand, a melting point of 85 ℃ and an acid value of 1 with a curing agent containing 50% by weight or more of hexamethylene diisocyanate which self-polymerizes into trimers and has a functionality of 3.4 and a ratio NCO/COOH of the number of moles of isocyanate groups in the curing agent (NCO value) to the number of moles of carboxyl groups in the acid-modified polypropylene (COOH value) of 3.6. The resulting solution-type mixture was applied to the metal surface of the composite film of the composite outer substrate resin layer opposite to the outer substrate resin layer, dried to form an inner adhesive layer having a thickness of 2 μm, and then heat-compounded with a heat-fusible resin layer of 40 μm at a temperature of 90 ℃ and then cured at a temperature of 50 ℃ for 7 days to form a composite product of the outer substrate resin layer (25 μm)/outer adhesive layer (3 μm)/intermediate metal layer/inner adhesive layer/inner heat-fusible resin layer (40 μm). The adhesive surface of the three-layer heat-fusible resin film in contact with the inner adhesive layer is subjected to corona treatment in advance.

Example 8

The outer base resin layer is a 25 μm thick biaxially oriented nylon film which is compounded to a 35 μm thick intermediate metal layer 8021 series aluminum material having a surface wettability of 68dyn/cm by an adhesive. Performing anti-corrosion treatment on two sides of the metal layer to form an anti-corrosion layer, wherein the anti-corrosion treatment comprises firstly forming 95 wt% cerium oxide (CeO) with the thickness of 0.1 mu m on the surface of the metal layer₂) And 5 wt% of aminopropyltrimethoxysilane, and a layer of an epichlorohydrin adduct of a polyallylamine resin and 1, 6-hexanediol was formed in a thickness of 0.1. mu.m.

A solution-type mixture was prepared by mixing an anhydrous maleic anhydride-modified polypropylene solution having a weight-average molecular weight of 25 ten thousand, a melting point of 85 ℃ and an acid value of 4 with a curing agent containing 50% by weight or more of hexamethylene diisocyanate which self-polymerizes into trimers and has a functionality of 3.4, and the ratio NCO/COOH of the number of moles of isocyanate groups in the curing agent (NCO value) to the number of moles of carboxyl groups in the acid-modified polypropylene (COOH value) was 3.6. The resulting solution-type mixture was applied to the metal surface of the composite film of the composite outer substrate resin layer opposite to the outer substrate resin layer, dried to form an inner adhesive layer having a thickness of 2 μm, and then heat-compounded with a heat-fusible resin layer of 40 μm at a temperature of 90 ℃ and then cured at a temperature of 50 ℃ for 7 days to form a composite product of the outer substrate resin layer (25 μm)/outer adhesive layer (3 μm)/intermediate metal layer/inner adhesive layer/inner heat-fusible resin layer (40 μm). The adhesive surface of the three-layer heat-fusible resin film in contact with the inner adhesive layer is subjected to corona treatment in advance.

Example 9

A solution-type mixture was prepared by mixing an anhydrous maleic anhydride-modified polypropylene solution having a weight-average molecular weight of 25 ten thousand, a melting point of 130 ℃ and an acid value of 2 with a curing agent containing 50% by weight or more of hexamethylene diisocyanate which self-polymerizes into trimers and has a functionality of 3.4 and a ratio NCO/COOH of the number of moles of isocyanate groups in the curing agent (NCO value) to the number of moles of carboxyl groups in the acid-modified polypropylene (COOH value) of 3.6. The resulting solution-type mixture was applied to the metal surface of the composite film of the composite outer substrate resin layer opposite to the outer substrate resin layer, dried to form an inner adhesive layer having a thickness of 2 μm, and then heat-compounded with a heat-fusible resin layer of 40 μm at a temperature of 90 ℃ and then cured at a temperature of 50 ℃ for 7 days to form a composite product of the outer substrate resin layer (25 μm)/outer adhesive layer (3 μm)/intermediate metal layer/inner adhesive layer/inner heat-fusible resin layer (40 μm). The adhesive surface of the three-layer heat-fusible resin film in contact with the inner adhesive layer is subjected to corona treatment in advance.

Comparative example 1

A solution-type mixture was prepared by mixing an anhydrous maleic anhydride-modified polypropylene solution having a weight-average molecular weight of 25 ten thousand, a melting point of 85 ℃ and an acid value of 2 with a curing agent containing 50% by weight or more of hexamethylene diisocyanate which self-polymerizes into a trimer having a functionality of 2.0, and the ratio NCO/COOH of the number of moles of isocyanate groups in the curing agent (NCO value) to the number of moles of carboxyl groups in the acid-modified polypropylene (COOH value) was 3.6. The resulting solution-type mixture was applied to the metal surface of the composite film of the composite outer substrate resin layer opposite to the outer substrate resin layer, dried to form an inner adhesive layer having a thickness of 2 μm, and then heat-compounded with a heat-fusible resin layer of 40 μm at a temperature of 90 ℃ and then cured at a temperature of 50 ℃ for 7 days to form a composite product of the outer substrate resin layer (25 μm)/outer adhesive layer (3 μm)/intermediate metal layer/inner adhesive layer/inner heat-fusible resin layer (40 μm). The adhesive surface of the three-layer heat-fusible resin film in contact with the inner adhesive layer is subjected to corona treatment in advance.

Comparative example 2

A solution-type mixture was prepared by mixing an anhydrous maleic anhydride-modified polypropylene solution having a weight-average molecular weight of 25 ten thousand, a melting point of 85 ℃ and an acid value of 2 with a curing agent containing 50% by weight or more of hexamethylene diisocyanate which self-polymerizes into a trimer having a functionality of 5.0, and the ratio NCO/COOH of the number of moles of isocyanate groups in the curing agent (NCO value) to the number of moles of carboxyl groups in the acid-modified polypropylene (COOH value) was 3.6. The resulting solution-type mixture was applied to the metal surface of the composite film of the composite outer substrate resin layer opposite to the outer substrate resin layer, dried to form an inner adhesive layer having a thickness of 2 μm, and then heat-compounded with a heat-fusible resin layer of 40 μm at a temperature of 90 ℃ and then cured at a temperature of 50 ℃ for 7 days to form a composite product of the outer substrate resin layer (25 μm)/outer adhesive layer (3 μm)/intermediate metal layer/inner adhesive layer/inner heat-fusible resin layer (40 μm). The adhesive surface of the three-layer heat-fusible resin film in contact with the inner adhesive layer is subjected to corona treatment in advance.

Comparative example 3

A solution-type mixture was prepared by mixing an anhydrous maleic anhydride-modified polypropylene solution having a weight-average molecular weight of 25 ten thousand, a melting point of 85 ℃ and an acid value of 0.8 with a curing agent containing 50% by weight or more of hexamethylene diisocyanate which self-polymerizes into a trimer having a functionality of 3.4 and a ratio NCO/COOH of the number of moles of isocyanate groups (NCO value) in the curing agent to the number of moles of carboxyl groups (COOH value) in the acid-modified polypropylene of 3.6. The resulting solution-type mixture was applied to the metal surface of the composite film of the composite outer substrate resin layer opposite to the outer substrate resin layer, dried to form an inner adhesive layer having a thickness of 2 μm, and then heat-compounded with a heat-fusible resin layer of 40 μm at a temperature of 90 ℃ and then cured at a temperature of 50 ℃ for 7 days to form a composite product of the outer substrate resin layer (25 μm)/outer adhesive layer (3 μm)/intermediate metal layer/inner adhesive layer/inner heat-fusible resin layer (40 μm). The adhesive surface of the three-layer heat-fusible resin film in contact with the inner adhesive layer is subjected to corona treatment in advance.

Comparative example 4

A solution-type mixture was prepared by mixing an anhydrous maleic anhydride-modified polypropylene solution having a weight-average molecular weight of 25 ten thousand, a melting point of 85 ℃ and an acid value of 5.5 with a curing agent containing 50% by weight or more of hexamethylene diisocyanate which self-polymerizes into a trimer having a functionality of 3.4 and a ratio NCO/COOH of the number of moles of isocyanate groups (NCO value) in the curing agent to the number of moles of carboxyl groups (COOH value) in the acid-modified polypropylene of 3.6. The resulting solution-type mixture was applied to the metal surface of the composite film of the composite outer substrate resin layer opposite to the outer substrate resin layer, dried to form an inner adhesive layer having a thickness of 2 μm, and then heat-compounded with a heat-fusible resin layer of 40 μm at a temperature of 90 ℃ and then cured at a temperature of 50 ℃ for 7 days to form a composite product of the outer substrate resin layer (25 μm)/outer adhesive layer (3 μm)/intermediate metal layer/inner adhesive layer/inner heat-fusible resin layer (40 μm). The adhesive surface of the three-layer heat-fusible resin film in contact with the inner adhesive layer is subjected to corona treatment in advance.

Comparative example 5

A solution-type mixture was prepared by mixing an anhydrous maleic anhydride-modified polypropylene solution having a weight-average molecular weight of 12 ten thousand, a melting point of 55 ℃ and an acid value of 2 with a curing agent containing 50% by weight or more of hexamethylene diisocyanate which self-polymerizes into trimers and has a functionality of 3.4 and a ratio NCO/COOH of the number of moles of isocyanate groups in the curing agent (NCO value) to the number of moles of carboxyl groups in the acid-modified polypropylene (COOH value) of 3.6. The resulting solution-type mixture was applied to the metal surface of the composite film of the composite outer substrate resin layer opposite to the outer substrate resin layer, dried to form an inner adhesive layer having a thickness of 2 μm, and then heat-compounded with a heat-fusible resin layer of 40 μm at a temperature of 90 ℃ and then cured at a temperature of 50 ℃ for 7 days to form a composite product of the outer substrate resin layer (25 μm)/outer adhesive layer (3 μm)/intermediate metal layer/inner adhesive layer/inner heat-fusible resin layer (40 μm). The adhesive surface of the three-layer heat-fusible resin film in contact with the inner adhesive layer is subjected to corona treatment in advance.

Comparative example 6

A solution-type mixture was prepared by mixing an anhydrous maleic anhydride-modified polypropylene solution having a weight-average molecular weight of 25 ten thousand, a melting point of 140 ℃ and an acid value of 2 with a curing agent containing 50% by weight or more of hexamethylene diisocyanate which self-polymerizes into trimers and has a functionality of 3.4 and a ratio NCO/COOH of the number of moles of isocyanate groups in the curing agent (NCO value) to the number of moles of carboxyl groups in the acid-modified polypropylene (COOH value) of 3.6. The resulting solution-type mixture was applied to the metal surface of the composite film of the composite outer substrate resin layer opposite to the outer substrate resin layer, dried to form an inner adhesive layer having a thickness of 2 μm, and then heat-compounded with a heat-fusible resin layer of 40 μm at a temperature of 90 ℃ and then cured at a temperature of 50 ℃ for 7 days to form a composite product of the outer substrate resin layer (25 μm)/outer adhesive layer (3 μm)/intermediate metal layer/inner adhesive layer/inner heat-fusible resin layer (40 μm). The adhesive surface of the three-layer heat-fusible resin film in contact with the inner adhesive layer is subjected to corona treatment in advance.

Comparative example 7

A solution-type mixture was prepared by mixing an anhydrous maleic anhydride-modified polypropylene solution having a weight-average molecular weight of 8.5 ten thousand, a melting point of 85 ℃ and an acid value of 2 with a curing agent containing 50% by weight or more of hexamethylene diisocyanate which self-polymerizes into a trimer having a functionality of 3.4 and a ratio NCO/COOH of the number of moles of isocyanate groups (NCO value) in the curing agent to the number of moles of carboxyl groups (COOH value) in the acid-modified polypropylene of 3.6. The resulting solution-type mixture was applied to the metal surface of the composite film of the composite outer substrate resin layer opposite to the outer substrate resin layer, dried to form an inner adhesive layer having a thickness of 2 μm, and then heat-compounded with a heat-fusible resin layer of 40 μm at a temperature of 90 ℃ and then cured at a temperature of 50 ℃ for 7 days to form a composite product of the outer substrate resin layer (25 μm)/outer adhesive layer (3 μm)/intermediate metal layer/inner adhesive layer/inner heat-fusible resin layer (40 μm). The adhesive surface of the three-layer heat-fusible resin film in contact with the inner adhesive layer is subjected to corona treatment in advance.

Comparative example 8

A solution-type mixture was prepared by mixing an anhydrous maleic anhydride-modified polypropylene solution having a weight-average molecular weight of 28 ten thousand, a melting point of 85 ℃ and an acid value of 2 with a curing agent containing 50% by weight or more of hexamethylene diisocyanate which self-polymerizes into trimers and has a functionality of 3.4 and a ratio NCO/COOH of the number of moles of isocyanate groups in the curing agent (NCO value) to the number of moles of carboxyl groups in the acid-modified polypropylene (COOH value) of 3.6. The resulting solution-type mixture was applied to the metal surface of the composite film of the composite outer substrate resin layer opposite to the outer substrate resin layer, dried to form an inner adhesive layer having a thickness of 2 μm, and then heat-compounded with a heat-fusible resin layer of 40 μm at a temperature of 90 ℃ and then cured at a temperature of 50 ℃ for 7 days to form a composite product of the outer substrate resin layer (25 μm)/outer adhesive layer (3 μm)/intermediate metal layer/inner adhesive layer/inner heat-fusible resin layer (40 μm). The adhesive surface of the three-layer heat-fusible resin film in contact with the inner adhesive layer is subjected to corona treatment in advance.

Comparative example 9

A solution-type mixture was prepared by mixing an anhydrous maleic anhydride-modified polypropylene solution having a weight-average molecular weight of 25 ten thousand, a melting point of 85 ℃ and an acid value of 2 with a curing agent containing 50% by weight or more of hexamethylene diisocyanate which self-polymerizes into trimers and has a functionality of 3.4, and the ratio NCO/COOH of the number of moles of isocyanate groups in the curing agent (NCO value) to the number of moles of carboxyl groups in the acid-modified polypropylene (COOH value) was 0.5. The resulting solution-type mixture was applied to the metal surface of the composite film of the composite outer substrate resin layer opposite to the outer substrate resin layer, dried to form an inner adhesive layer having a thickness of 2 μm, and then heat-compounded with a heat-fusible resin layer of 40 μm at a temperature of 90 ℃ and then cured at a temperature of 50 ℃ for 7 days to form a composite product of the outer substrate resin layer (25 μm)/outer adhesive layer (3 μm)/intermediate metal layer/inner adhesive layer/inner heat-fusible resin layer (40 μm). The adhesive surface of the three-layer heat-fusible resin film in contact with the inner adhesive layer is subjected to corona treatment in advance.

Comparative example 10

A solution-type mixture was prepared by mixing an anhydrous maleic anhydride-modified polypropylene solution having a weight-average molecular weight of 25 ten thousand, a melting point of 85 ℃ and an acid value of 2 with a curing agent containing 50% by weight or more of hexamethylene diisocyanate which self-polymerizes into trimers and has a functionality of 3.4 and a ratio NCO/COOH of the number of moles of isocyanate groups in the curing agent (NCO value) to the number of moles of carboxyl groups in the acid-modified polypropylene (COOH value) of 7.0. The resulting solution-type mixture was applied to the metal surface of the composite film of the composite outer substrate resin layer opposite to the outer substrate resin layer, dried to form an inner adhesive layer having a thickness of 2 μm, and then heat-compounded with a heat-fusible resin layer of 40 μm at a temperature of 90 ℃ and then cured at a temperature of 50 ℃ for 7 days to form a composite product of the outer substrate resin layer (25 μm)/outer adhesive layer (3 μm)/intermediate metal layer/inner adhesive layer/inner heat-fusible resin layer (40 μm). The adhesive surface of the three-layer heat-fusible resin film in contact with the inner adhesive layer is subjected to corona treatment in advance.

The test method comprises the following steps:

1. resin melting point measurement of inner adhesive layer

The test was carried out using a Differential Scanning Calorimeter (Differential Scanning Calorimeter), and the temperature increase and decrease rates were set at 10 ℃/min, and four stages were set: (1) heating from 25 ℃ to 150 ℃, (2) cooling from 150 ℃ to 25 ℃, (3) heating from 25 ℃ to 150 ℃, (4) cooling from 150 ℃ to 25 ℃, and measuring the peak top temperature of the second endothermic peak thereof to obtain the melting point.

2. Resin molecular weight measurement of inner adhesive layer

The weight average molecular weight Mw of the polymer resin was measured using high temperature GPC.

And (3) testing conditions are as follows: the test temperature is 150 ℃; the mobile phase is Trichlorobenzene (TCB); the standard substance is Polystyrene (PS); the sample system is a polyolefin sample, such as: common samples PP and PE; the test sample amount was 5 mg.

The instrument model is as follows: PL-GPC 220; the type of the chromatographic column: PLgel MIXED-B LS 300 X7.5mm; a detector: a differential refractive detector.

Sample preparation: the sample is completely dissolved in trichlorobenzene, filtered by a 0.22 mu m organic filter membrane and directly tested on a machine, and the test value of the weight average molecular weight Mw is directly read.

3. Acid value measurement of inner adhesive layer

Dissolving the inner adhesive layer into a sample solution by using an organic solvent, neutralizing the titrated sample solution by using a standard titration solution of potassium hydroxide (KOH) or sodium hydroxide (NaOH), judging a titration end point according to the corresponding color change of the indicator, and finally calculating the acid value of the sample solution according to the volume of the standard titration solution consumed by the end point. The calculation formula is as follows:

Δ V: titration of the number of volumes (ml) of KOH or NaOH consumed;

c: molar concentration (mol/L) of KOH or NaOH standard solutions;

m: mass of resin (g).

4. Functionality measurement of curing agents

(1) Apparatus, chromatographic conditions and reagents

The instrument comprises the following steps: LC-10AD type high performance liquid chromatography, manufactured by Shimadzu corporation, Japan;

a chromatographic column: three chromatographic columns, such as GPC-802, GPC-8025 and GPC-803, were used in series, manufactured by Shimadzu corporation, Japan;

a detector: a differential refraction detector (RI);

the column temperature was 35 ℃; the flow rate is 1.0 mL/min; the sample injection amount is 20L; the sample concentration is 0.002 g/mL; tetrahydrofuran (THF) and methanol were both chromatographically pure.

(2) Sample derivatization treatment

1g of the sample was weighed in a 250mL iodine flask, and 20mL of methanol was added to the iodine flask and sufficiently shaken to completely disperse the sample in the methanol. Then placing the mixture into a constant-temperature water bath at 70 ℃ for refluxing for 2h, taking out the mixture, naturally volatilizing excessive methanol in a fume hood, and then placing the mixture into a vacuum oven to dry for 2h at 50 ℃ to obtain the yellow viscous derivative.

(3) Sample GPC measurement

And weighing a small amount of derivative by using a 25mL weighing bottle, adding THF (tetrahydrofuran) to prepare a solution of 0.002g/mL, after the sample is fully dissolved, extracting the excessive solution by using a syringe, injecting the excessive solution into a six-way valve, and simultaneously opening an integrator to obtain the chromatographic peak of Gel Permeation Chromatography (GPC) of each functional component in the sample.

And calculating the relative content of peak areas of the components by using a normalization method to characterize the mass fraction of the components. The calculation formula is as follows:

and Wi: is the mass fraction of the i-functional component in the sample;

a: GPC chromatogram peak area of i-functional component in sample.

5. NCO/COOH number

The ratio (NCO/COOH) value between the number of moles of isocyanate groups in the curing agent (NCO value) and the number of moles of carboxyl groups in the base acid-modified polypropylene (COOH value) was calculated from the amounts of the base acid-modified polypropylene and the curing agent added. The calculation formula is as follows:

NCO%: effective mass of NCO in the curing agent;

nv%: and (3) solid content.

6. Initial peel strength test

Initial peel strength test

Preparing a finished metal composite film into a straight strip shape, wherein the size of a sample strip is 100x15mm, carrying out an interlayer peeling test of an intermediate metal layer and an internal heat welding resin layer by using a tensile test device, placing a peeled internal heat welding resin layer film in an upper clamping plate and an intermediate metal layer in a lower clamping plate of a stretching test device, carrying out T-shaped peeling with a peeling surface of 180 degrees under the condition that the stretching speed is 50mm/min, and starting to measure the peeling strength between the intermediate metal layer and the internal heat welding resin layer.

The peel strength was read in such a manner that the moving distance of the inner heat-fusible resin layer and the intermediate metal layer was 50mm, and the average value of the peel strengths was selected from the moving distances of 10mm to 40 mm. 5/group were tested in parallel.

7. Electrolyte resistance test of finished product

Directly soaking the metal composite film finished sample strip in a solution containing 1M LiPF₆Dimethyl carbonate (DMC): diethyl carbonate (DEC): soaking the mixture in a mixed solvent with Ethylene Carbonate (EC) in a weight ratio of 1:1:1 at 85 ℃ for 1 day, 3 days, 7 days and 14 days, taking out, washing with water for 20min, wiping off the moisture on the surface of a sample strip, and measuring the peel strength between the intermediate metal layer and the internal heat welding resin layer according to the initial peel strength test method of a finished product.

8. Water-adding electrolyte resistance test of finished product

Directly soaking the metal composite film finished sample strip in a solution containing 1M LiPF₆Dimethyl carbonate (DMC): carbonic acid diethyl ester(DEC): adding an aqueous solution accounting for 1000PPM of the total mass of the electrolyte into a mixed solvent with the weight ratio of Ethylene Carbonate (EC) being 1:1:1, soaking for 1 day, 3 days, 7 days and 14 days at the temperature of 85 ℃, taking out, washing with water for 20min, wiping off the surface moisture of the sample strip, and measuring the peel strength between the intermediate metal layer and the internal heat welding resin layer according to the initial peel strength test method of the finished product.

As listed in table 1 below, the solution-type mixture of comparative example 6 was too viscous to be uniformly applied, so that the initial strength of the resulting composite product was extremely low, and thus other tests were impossible.

As listed in table 1 below and shown in fig. 2 to 5, example 1 differs from comparative examples 1, 2 in the functionality of the curing agent, but the characteristics of example 1 are superior to comparative examples 1, 2 as a whole; example 1 is different from comparative examples 3 and 4 in the acid value of the acid-modified polypropylene, but the characteristics of example 1 are superior to those of comparative examples 3 and 4 as a whole; example 1 differs from comparative examples 5 and 6 in the melting point of the acid-modified polypropylene, but the characteristics of example 1 are superior to those of comparative examples 5 and 6 as a whole; example 1 differs from comparative examples 7 and 8 in the molecular weight of the acid-modified polypropylene, but the characteristics of example 1 are superior to those of comparative examples 7 and 8 as a whole; example 1 differs from comparative examples 9 and 10 in the NCO/COOH value, but example 1 is superior in characteristics to comparative examples 9 and 10 as a whole.

As shown in table 1 below and fig. 2 to 5, it is understood that the characteristics of example 9 are best as a whole by comparing examples 1 to 9.

The above matters related to the common general knowledge are not described in detail and can be understood by those skilled in the art.

The present invention is not intended to be limited to the particular embodiments shown and described, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein. The technical scope of the present invention is not limited to the content of the specification, and must be determined according to the scope of the claims.

TABLE 1

Claims

1. A metal composite film, comprising:

a metal layer, a first adhesive layer, and a first thermal welding resin layer;

the first adhesive layer is arranged between the metal layer and the first hot-melt resin layer, and at least contains a curing agent and acid modified polypropylene;

the curing agent contains more than 50 wt% of hexamethylene diisocyanate, the hexamethylene diisocyanate self-polymerizes into trimer, and the functionality of the hexamethylene diisocyanate is 3.0-4.5;

the acid-modified polypropylene contains polypropylene resin, the polypropylene resin is modified by carboxylic acid or anhydride thereof through grafting treatment, the acid value of the acid-modified polypropylene is 1 to 5, the melting point is 70 to 130 ℃, and the weight-average molecular weight is 10 to 25 ten thousand;

the ratio NCO/COOH of the number of moles of isocyanate groups (NCO value) in the curing agent to the number of moles of carboxyl groups (COOH value) in the acid-modified polypropylene is 1.0 to 5.0.

2. The metal composite film according to claim 1, wherein the carboxylic acid comprises one or more of maleic acid, fumaric acid, acrylic acid, and methacrylic acid, and the anhydride comprises one or more of maleic anhydride, fumaric anhydride, acrylic anhydride, and methacrylic anhydride.

3. The metal composite film according to claim 1, further comprising:

the first anti-corrosion layer is formed between the metal layer and the first adhesive layer, and the second anti-corrosion layer is formed on one side of the metal layer, which is far away from the first adhesive layer.

4. The metal composite film according to claim 3, wherein the first corrosion prevention layer and the second corrosion prevention layer each comprise a trivalent chromium compound, an inorganic acid, and an organic resin.

5. The metal composite film according to claim 4, wherein the trivalent chromium compound comprises one or more of chromium nitrate, chromium phosphate, chromium fluoride, and chromium chloride; and/or the inorganic acid comprises one or more of nitric acid and phosphoric acid; and/or the organic resin comprises one or more of polyacrylic resin and polyvinyl alcohol; and/or the polyacrylic resin has a weight average molecular weight of 1 to 80 ten thousand; and/or the mass ratio between the trivalent chromium compound, the inorganic acid and the organic resin is (18 to 60): (3 to 60): (6 to 60); and/or the mass ratio between the trivalent chromium compound and the organic resin is (3 to 100): 10.

6. the metal composite film according to claim 5, wherein each of the first corrosion prevention layer and the second corrosion prevention layer further comprises a fluoride, and a mass ratio between the trivalent chromium compound, the inorganic acid, the organic resin, and the fluoride is (18 to 60): (3 to 60): (6 to 60): (0 to 10), the corresponding value for said fluoride being other than 0.

7. The metal composite film according to claim 4, wherein the trivalent chromium compound comprises one or more of chromium nitrate, chromium fluoride, chromium chloride, and chromium phosphate; and/or the inorganic acid comprises one or more of nitric acid and hydrofluoric acid; and/or the organic resin comprises at least polyvinyl alcohol; and/or the mass ratio between the trivalent chromium compound, the inorganic acid and the organic resin is (24 to 40): (1 to 8): (10 to 12); and/or the mass ratio between the trivalent chromium compound and the organic resin is (2 to 4): 1.

8. the metal composite film according to claim 7, wherein the first corrosion prevention layer and the second corrosion prevention layer each further comprise a titanate, and a mass ratio between the trivalent chromium compound, the inorganic acid, the organic resin, and the titanate is (24 to 40): (1 to 8): (10 to 12): (0 to 5), the corresponding value of the titanate being other than 0.

9. The metal composite film according to claim 3, wherein the first corrosion prevention layer and the second corrosion prevention layer each comprise an aminated phenol polymer, a trivalent chromium compound, and a phosphorus compound.

10. The metal composite film according to claim 9, wherein the first corrosion prevention layer and the second corrosion prevention layer are formed every 1m²The aminated phenol polymer can be 1 to 200mg by area, the chromium element in the trivalent chromium compound can be 0.5 to 50mg, and the phosphorus element in the phosphorus compound can be 0.5 to 50 mg.

11. The metallic composite film according to claim 3, wherein the first corrosion prevention layer comprises a first corrosion prevention sublayer and a second corrosion prevention sublayer, the second corrosion prevention layer comprises a first corrosion prevention sublayer and a second corrosion prevention sublayer, the first corrosion prevention sublayer of the first corrosion prevention layer is formed on a side close to the metallic layer, the second corrosion prevention sublayer of the first corrosion prevention layer is formed on the other side far from the metallic layer, the first corrosion prevention sublayer of the second corrosion prevention layer is formed on a side close to the metallic layer, and the second corrosion prevention sublayer of the second corrosion prevention layer is formed on the other side far from the metallic layer.

12. The metal composite film according to claim 11, wherein a first corrosion sub-layer of the first corrosion protection layer and a first corrosion sub-layer of the second corrosion protection layer comprise cerium oxide, phosphoric acid, or phosphate; and/or the second corrosion protection sublayer in the second corrosion protection layer and the second corrosion protection sublayer in the second corrosion protection layer comprise a polymeric cationic or anionic polymer.

13. The metal composite film according to claim 12, wherein in the case where the first corrosion prevention sublayer in the first corrosion prevention layer and the first corrosion prevention sublayer in the second corrosion prevention layer comprise cerium oxide and phosphoric acid or phosphate, 1 to 100 parts by mass of phosphoric acid or phosphate is contained in the presence of 100 parts by mass of cerium oxide.

14. The metal composite film according to claim 1, wherein the first thermal welding resin layer comprises, in order from a side close to the first adhesive layer to another side far from the first adhesive layer: an outer resin layer, an intermediate resin layer, and an inner resin layer.

15. The metal composite film according to claim 14, wherein the outer resin layer comprises random copolymer polypropylene having a melting point of 140 to 160 ℃ and a 230 ℃ melt index MFR of 4.5 to 6.5g/10 min; and/or the middle resin layer comprises a block copolymerized polypropylene, a random copolymerized polypropylene, a polymer elastomer composed of propylene-butene, and a non-crystalline propylene-based elastomer, the melting point of the block copolymerized polypropylene is 150 to 170 ℃, the 230 ℃ melt index MFR of the block copolymerized polypropylene is 1 to 4g/10min, the content of the block copolymerized polypropylene with respect to the middle resin layer is 40 to 60 wt%, the melting point of the random copolymerized polypropylene is 140 to 170 ℃, the 230 ℃ melt index MFR of the random copolymerized polypropylene is 4 to 7g/10min, the content of the random copolymerized polypropylene with respect to the middle resin layer is 10 to 30 wt%, the melting point of the polymer elastomer composed of propylene-butene is 150 to 170 ℃, the 230 ℃ melt index MFR of the polymer elastomer composed of propylene-butene is 8 to 12g/10min, the content of the polymer elastomer composed of propylene-butene with respect to the middle resin layer is 10 to 30 wt%, the amorphous propylene-based elastomer has a 230 ℃ melt index MFR of 2 to 4g/10min, and the content of the amorphous propylene-based elastomer with respect to the intermediate resin layer is 5 to 15 wt%; and/or the inner resin layer comprises a random copolymer polypropylene having a melting point of 135 to 155 ℃ and a 230 ℃ melt index MFR of 10 to 15g/10 min; and/or the thickness ratio of the outer resin layer, the intermediate resin layer, and the inner resin layer is (1 to 5): (4 to 8): 1.

16. A method of preparing the metal composite film according to any one of claims 1 to 13, comprising:

providing the metal layer;

forming the first adhesive layer on the metal layer; and

and forming the first thermal welding resin layer on one side of the first adhesive layer relative to the metal layer.